The present invention relates generally to storage battery ventilation, and more particularly, to an improved vent for use in connection with conventional storage battery designs.
As a result of various chemical processes which occur when conventional storage batteries are in use, as well as during the charging of such storage batteries, gases such as hydrogen and oxygen are often produced. Such gases are generally vented to the atmosphere in order to relieve the battery of internal pressures which would otherwise result. In performing such ventilation, the following two factors should be considered.
First, since the gases being vented are hydrogen and oxygen, care must be taken to avoid the possibility of igniting such gases. This is particularly so during battery charging, since gassing becomes more prevalent during such periods, and since electrical connections made to the terminals of the battery can create a potential for sparks. Failure to adequately accommodate such conditions can result in sparks or ignited gases re-entering the battery, at times resulting in battery explosion.
Second, care must be taken to prevent the loss of battery electrolyte through the vent, either as a result of misting which occurs in connection with battery gassing, or as a result of battery movement. Otherwise, battery electrolyte levels must be carefully monitored and replenished, as needed, requiring additional servicing procedures and often compromising the service life of the battery.
A variety of devices have been developed in an attempt to accommodate the foregoing difficulties by providing a vent cap which is both safe and reliable in operation, yet inexpensive in manufacture. In an effort to prevent sparks and ignited gases from re-entering the battery, such vent caps are generally provided with proportioned apertures or slits which are sufficiently large to enable the safe ventilation of gases from the battery, yet which are sufficiently small to prevent the passage of sparks or ignited gases. To prevent the loss of electrolyte, such vent caps are generally provided with baffles or passageways which develop relatively contorted flow paths designed to condense and facilitate the return of electrolyte collected within the vent cap to the cell of the battery with which the vent cap is associated.
Although providing adequate operation in many circumstances, such vent caps have often been found to be unacceptable from a manufacturing standpoint. In particular, it has generally been found difficult to accurately maintain the dimensions of the apertures or slits provided to ventilate gases to the atmosphere, as well as to produce the baffles or passageways provided to control the escape of electrolyte. Simplifying the vent cap's structure would enable reductions in manufacturing costs, but has generally been found to unacceptably compromise safety and reliability in operation.
The need therefore remained to develop a safe and reliable vent cap which is sufficiently simple in construction to enable its manufacture at reasonable cost.